Rigorous phase-space approach to topological impurity effects in thermal transport

Coming soon!

Tuning transport in solid-state Bose-Fermi mixtures by Feshbach resonances

Transition metal dichalcogenide (TMD) heterostructures have emerged as promising platforms for realizing tunable Bose-Fermi mixtures with comparable (and large) densities of fermions and bosons at low relative temperatures. We predict the transport properties of such Bose-Fermi mixtures close to a narrow solid-state Feshbach resonance. When driving a hole current, the response of all constituents of the mixture (doped holes, excitons, and trions) are significantly impacted by the resonant interactions. Our results on the temperature-dependent conductivities demonstrate that resonant interaction effects actually dominate the transport response in these solid-state Bose-Fermi mixtures.

Phys. Rev. Lett. 134, 126502.
Links: arXiv version, journal version.

Anomalous quantum oscillations from boson-mediated interband scattering

Quantum oscillations (QO) in metals refer to the periodic variation of thermodynamic and transport properties as a function of inverse applied magnetic field. QO frequencies are normally associated with semi-classical trajectories of Fermi surface orbits. Here, we develop a theory of composite frequency quantum oscillations (CFQO) in 2D Fermi liquids with several Fermi surfaces and interband scattering mediated by a dynamical boson. Specifically, we show that CFQO arise from oscillations in the fermionic self-energy with anomalous frequency splitting and distinct strongly non-standard temperature dependencies.

Phys. Rev. Lett. 134, 146502.
Links: arXiv version, journal version.

Geometric effects and thermal currents in non-coplanar magnetic textures

Coming soon!

Emergent Gauge Theories in Spin-Orbital Loop Models

We are developing a parton construction for defects in fluctuating loop states emerging from spin-orbital models in three spatial dimension. This allows us to explore spin-liquid-like phases and critical points of lattice gauge theories while evading confinement in the U(1) sector, as well as various striped ordered phases.

This project is at an intermediate stage of progress.

Quantum kinetic equation and thermal conductivity tensor for bosons

How can one study the intrinsic thermal Hall conductivity of bosons from a kinetic equation viewpoint? We show that this arises from identifying, in phase space, the correct choice of "kinetic coordinates" which allows to diagonalize the evolution operator in a gauge-invariant way, using the formalism of the star-product. We obtain the local energy current operator for any quadratic theory of chiral bosons without assuming translational invariance, which allows to study locally the edge currents as well as inhomogeneous systems.

Phys. Rev. B 109, 235137.
Links: arXiv version, journal version.

Thermal Hall conductivity from inelastic scattering of phonons by fermionic spinons

What are mechanisms for a phonon thermal Hall effect in insulators that do not exhibit magnetic order? We are studying the inelastic scattering of phonons with fermionic spinons in quantum spin liquids, and more generally with fermions (be they neutral or charged) in various contexts, and the mechanisms whereby a thermal Hall conductivity may appear.

This project has changed shape multiple times and is now in its final stages of completion.

Thermal Conductivity and theory of inelastic scattering of phonons by collective fluctuations

We study the intrinsic scattering of phonons by a general quantum degree of freedom, i.e. a fluctuating “field” Q, which may have completely general correlations, restricted only by unitarity and translational invariance. From the induced scattering rates, related to two- and four- point correlations of the Q field, we calculate the thermal conductivity tensor of the phonons. We obtain general and explicit forms for these correlations which isolate the contributions to the Hall conductivity, and provide a general discussion of the implications of symmetry and equilibrium. This mostly analytical work contains many more interesting details, which unfortunately this paragraph is too short to explain.

Phys. Rev. B 106, 245139. Featured in Physics, Editor's Suggestion.
Links: arXiv version, journal version.

Phonon thermal Hall conductivity from scattering with collective fluctuations

Because electrons and ions form a coupled system, it is a priori clear that the dynamics of the lattice should reflect symmetry breaking within the electronic degrees of freedom. This is reflected in the thermal Hall effect of phonons. How are time-reversal breaking and chirality communicated to the lattice? In this paper we discuss how this occurs via many-body scattering of phonons by collective modes. We derive fundamental new results for such skew scattering and the consequent thermal Hall conductivity. We apply our analytical formalism, and provide numerical evaluations, in ordered antiferromagnets.

Phys. Rev. X 12, 041031. Featured in Physics: see Viewpoint.
Links: arXiv version, journal version.

Condensation with Two Constraints and Disorder

When a set of positive random variables is constrained by two global conservation laws, it may undergo a 'condensation' transition, whereby a few randomly picked variables carry all the weight. This may be understood as ergodicity breaking on intermediate time scales, because exploration of the full phase space manifold is (dramatically) frustrated due to the global constraints. Now, how does disorder affect the microcanonical statistics of such classical systems? This is what we investigate here, both analytically and numerically.

J. Stat. Mech. (2018) 043211.
Links: arXiv version, journal version.